It is either what @nullama said (people trying to get into the halving block) or this is "fee market manipulation" considering the timing and how the attack took place. There was an "artificial" injection of a rather large number of transactions (the first suspect is the Ordinals Attackers) into the mempool which has only manipulated the fee market and significantly increased the fee rate by creating this fake competition.

Luckily the attack is becoming very expensive so it can not continue for long but the attack itself will not stop as long as the exploit in the protocol exists and the fake market where they sell fake tokens under the codename Ordinals exists. That is creating an incentive to spam attack bitcoin.